1. Field of the Invention
This invention relates to electronic musical instruments and more particularly to a circuit for controlling bass signals in such an instrument.
2. The Prior Art
Electronic organs normally have an upper keyboard for playing melody notes, a lower keyboard for playing chord or accompaniment notes, and a pedal board for playing bass notes. In order to simplify playing of the organ, some recent models have incorporated an automatic bass feature which permits additional outputs to be obtained when one or more keys on a manual keyboard are depressed which outputs are utilized to control the application of selected bass tone signals to the output. This control may, for example, include the alternate playing of the selected bass notes under control of a rhythm generating devise. Thus, the selected high and low bass notes may be alternatively sounded or the selected root and fifth notes may be alternatively sounded under control of the organs rhythm generator.
Heretofore, if the musician operated the bass pedals while the organ was providing automatic bass outputs, both sets of outputs would be provided to the organ amplifiers and speakers. This double signal could cause the power capabilities of the amplifiers and speakers to be exceeded, causing distortion in the output from and possible damage to these elements. In addition, the sounding of notes from the two different bass sources simultaneously could produce a musically unpleasant sound. However, without the facility of generating bass notes from the pedal board, the musical capabilities of the instrument are somewhat restricted. For example, it is not possible to hold a selected one or more bass notes while changing lower keyboard notes when operating in the automatic bass mode. A need therefore exists for an inexpensive and simple circuit to permit automatic bass notes to be suppressed when the musician elects to play notes from the pedal board and to return to an automatic bass mode when playing of notes from the pedal board terminates.